These projects are directed towards a greater understanding of the quaternary organization of plasma lipoproteins and of the function of the oligomeric species involved in the transport and metabolism of lipids in plasma. The apolipoprotein composition of plasma lipoproteins is viewed as the governing factor in directing lipoprotein metabolism. Specificity is believed to be related directly to apo-lipoprotein secondary, tertiary and quaternary structure. Studies of the hydrodynamic properties of "lipid free" apolipoproteins, have been extended to include nitrated, sulfenylated and iodinated apolipoproteins in order to screen modification techniques commonly used for investigating lipoprotein metabolism. Analysis of the molecular properties of the specific self-associated and mixed-associated oligomeric apolipoprotein complexes (modified and native) are of major importance to our ultimate understanding of plasma lipoprotein metabolism.